Harness Model Router

Harness Model Router

Classify a list of parallel task descriptions by complexity and emit a routing table that maps each task to a model tier. You do this yourself — read each task description and apply the classification procedure below.

When to run

• Called by harness-orchestrator at step 5, immediately before building the Agent() call list for independent parallel tasks.
• No-op for serial tasks — only invoke when tasks are genuinely parallel.

Procedure

1. Receive the parallel task list

Take the list of parallel task descriptions from harness-orchestrator. Each entry is a short description of independent work.

2. Classify each task

Apply both signals in order. Keywords can only upgrade a tier, never downgrade.

Signal 1 — Task type (primary signal)

| Task type | Tier | |---|---| | Read-only / explanation | haiku | | Trivial mutation (rename, typo, constant, comment) | haiku | | Code generation (component, endpoint, hook, service) | sonnet | | Standard feature addition | sonnet | | Cross-cutting reasoning (debug across layers, investigate) | opus | | Architecture / design / migration | opus |

Signal 2 — Keyword scan (confirms or upgrades)

| Keywords present | Tier signal | |---|---| | rename, typo, comment, explain, describe, list, show, format | haiku | | add, create, write, implement, update, build, generate, test, endpoint, component, hook | sonnet | | refactor, debug, design, architect, analyze, migrate, restructure, investigate, across, system-wide | opus |

Tie-breaking rules

• Ambiguous → sonnet. Never silently under-allocate.
• Multiple modules or layers mentioned → minimum sonnet. Upgrade to opus if opus keywords are also present.
• Keywords only upgrade. A haiku-type task with sonnet keywords becomes sonnet. Never the reverse.

3. Emit the routing table

Output the table in context (do not write to a file — it is ephemeral per dispatch):

ROUTING TABLE — 
  [1] ""   → haiku
  [2] ""   → sonnet
  [3] ""   → opus

The run identifier is a short label (e.g. the batch name or a sequential counter) so multiple routing calls in the same session are distinguishable.

harness-orchestrator reads this table and passes model: "" to each Agent call.

Model tier reference

| Tier | Model ID | Best for | |---|---|---| | haiku | claude-haiku-4-5-20251001 | Trivial mutations, read-only, explanations | | sonnet | claude-sonnet-4-6 | Code generation, standard feature work, tests | | opus | claude-opus-4-8 | Architecture, cross-cutting refactors, debugging across layers |

See also

• harness-orchestrator — invokes this skill before parallel dispatch
• superpowers:dispatching-parallel-agents — the dispatch mechanism this routing feeds into

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: chetan25
• Source: chetan25/harness-claude-skills
• License: MIT

Install and usage instructions live in the source repository linked above.